Technical Abstract:
Management of the rust disease of dry and snap beans is complicated by the ability of the bean rust pathogen to recurrently produce new virulent strains. The most effective strategy to manage this hyper-virulent pathogen is to grow bean varieties with very broad rust resistance; however, this requires an assortment of effective rust resistance genes. About a dozen rust resistance genes are available in common bean. None of them are resistance to all races of the rust pathogen. Recently we discovered that the domesticated tepary bean accession G 40022 had broad resistance to rust. When we conducted a study to compare the resistance in G 40022 with that of the rust resistance genes present in common bean, the results were outstanding. They revealed that the resistance in the tepary bean was determined by a single gene. More importantly, this was the only gene with resistance to all races of the rust pathogen used in this study. Thus, the new rust resistance in the tepary bean was broader in spectrum than any rust resistance gene present in common bean. These results are particularly useful to plant breeders and geneticists using rust resistance genes to manage a disease caused by a highly variable pathogen. The new resistant varieties that could be developed using this gene will benefit dry and snap bean producers.